A mobile phone or other mobile communication terminal device uses a standby mode or shutdown mode of an LSI provided by a vender when signaling information is not received while waiting so as to try to save power of the system (see for example Patent Document 1).
Further, the practice has been to not shut off the power to parts holding control data related to system control, but to use them in a state supplied with power at all times, and to stop the supply of power to only parts which do not have to hold data so as to thereby try to save power.
Up until now, this has not been necessary because of individual parts (ICs) were used. However, the trend is for combining ICs for greater integration of circuits. The reason for this is that the increasing small size of mobile phones has made it essential to save power and decrease the number of parts.
Further, as an analog high frequency circuit receiving and modulating/demodulating signals in a mobile phone, an RFIC is used.
For this RFIC as well, if not receiving signaling information when waiting, the supply of power to the RFIC is stopped so as to try to save power—but only in a case of use of an IC of an RF block of a type not holding control data inside it.
Patent Document 1: Japanese Patent Publication (A) No. 2006-211439